-1 means unknown projection, though for GeoJSON you can usually assume it's either going to have an EPSG code in there or it's 4326 (the only differences in Geo

-1 means unknown projection, though for GeoJSON you can usually assume it's either going to have an EPSG code in there or it's 4326 (the only differences in GeoJSON versions is that in newer versions of GeoJSON it HAS to be in 4326 and in older ones it could say it was something else but most things will break if they get a GeoJSON that's not 4326 even if the GeoJSON has it's CRS info in it).